Technical Field
The present invention generally is in the field of conversion kits for converting two wheeled motorized vehicles to three-wheeled motorized vehicles. The present invention also is in the field of conversion kits having a two-wheeled axle and offset drive assembly that is non-coaxial with the original one wheeled axle and is driven by a minimally adapted original drive assembly corresponding to the original one wheeled axle. The present invention additionally is in the field of conversion kits that are substantially within the unmodified footprint defined by the space around the original one wheeled axle. The invention further is in the field of conversion kits having a non-straddle, axle-supported differential and/or a braking assembly at least partially attached to a differential housing.
Prior Art
Like bicycles, two-wheel motorcycles rely on the ability of the rider to maintain balance of the vehicle when moving or at a rest. However, a three wheel motorcycle or motor-tricycle, often called a trike, having a “delta configuration” (i.e. one front wheel and two rear wheels) gives an ordinary motorcycle the inherent ability to remain upright when moving and at rest. This is possible due to the stance created from changing the dimensional stability of the motorcycle from vertical to horizontal with the replacement of the one rear wheel with two rear wheels that are spread far enough apart to create a stable platform.
Many efforts have been made to achieve this dimensional stability by the use of add on, outboard wheels. This creates a four wheel vehicle (one in front and three rear wheels) that retains the original rear wheel to provide the drive power. This is similar to the training wheels used on a child's first bicycle. This configuration gives riding and at rest stability but carries an often dangerous risk when cornering. With the outboard wheel configuration the outer tire will lift during most turns. When this happens the outboard tires and center drive wheel are usually rotating at different speeds because of their different diameters or distance from the center line of the vehicle. As the turn is completed the outer wheel comes back into contact with the road surface. That outer tire must now “spin up” its rotation to match the other tires. This spinning up causes a drag on that side of the vehicle with a corresponding braking action thus lurching the vehicle towards that side.
To eliminate this, most trike designs have gone to the delta configuration where the two rear wheels are on a solid axle or more commonly two axles joined by a differential unit. Most of these designs require extensive modification to the swing arm and even the motorcycle frame itself due to the weight of the rear assembly with its tires, fenders, and sometimes a fiberglass or metal full body. Many of these conversions use shortened versions of regular automobile rear ends. Their extensive use of all steel automotive components results in excessive weight behind the normal center of gravity of the vehicle. Additionally, these conversions tend to require special skills, special equipment, and often take weeks of shop time to accomplish.
Based upon these design compromises, it becomes apparent that what is needed is a rigid, light weight design that gives greater maneuverability, better mileage, and is readily adaptable to a variety of motorcycle makes and models. It is to these needs and others that the present invention is directed.